It sure looks like an anubias to me, though it is hard to say specifically what species. Maybe congensis, lanceolata, or azfelia.
Since you are going to need to plant it anyway, pull it out of the pot, clean off the rockwool, and see if it has a rhizome (a thick tuber-looking thing that the leaves and roots grow out of). If it does you will know for sure that it is an Anubias. If you are not sure what a rhizome looks like, post a pic of it out of the pot and we will be able to ID it a little more effectively.